pythongh-140406: Fix memory leak upon __hash__ returning a non-integer (pythonGH-140411)

(cherry picked from commit 71db05a)

Co-authored-by: Peter Bierma <[email protected]>

Author: ZeroIntensity

Lib/test/test_builtin.py

@@ -1183,6 +1183,16 @@ def __hash__(self):
                 return self
         self.assertEqual(hash(Z(42)), hash(42))
 
+    def test_invalid_hash_typeerror(self):
+        # GH-140406: The returned object from __hash__() would leak if it
+        # wasn't an integer.
+        class A:
+            def __hash__(self):
+                return 1.0
+
+        with self.assertRaises(TypeError):
+            hash(A())
+
     def test_hex(self):
         self.assertEqual(hex(16), '0x10')
         self.assertEqual(hex(-16), '-0x10')

Misc/NEWS.d/next/Core_and_Builtins/2025-10-21-06-51-50.gh-issue-140406.0gJs8M.rst

@@ -0,0 +1,2 @@
+Fix memory leak when an object's :meth:`~object.__hash__` method returns an
+object that isn't an :class:`int`.

Objects/typeobject.c

@@ -10195,6 +10195,7 @@ slot_tp_hash(PyObject *self)
         return PyObject_HashNotImplemented(self);
     }
     if (!PyLong_Check(res)) {
+        Py_DECREF(res);
         PyErr_SetString(PyExc_TypeError,
                         "__hash__ method should return an integer");
         return -1;